82 THE STONES OF VENICE CONSTRUCTION

and, in reasoning upon the superstructure, we shall never suppose it to be done. The mind of the spectator does not conceive it; and he estimates the merits of the edifice on the supposition of its being built upon the ground. Even if there be a vast tableland of foundation elevated for the whole of it, accessible by steps all round, as at Pisa,¹ the surface of this table is always conceived as capable of yielding somewhat to superincumbent weight, and generally is so; and we shall base all our arguments on the widest possible supposition, that is to say, that the building stands on a surface either of earth, or, at all events, capable of yielding in some degree to its weight.

§ 8. Now let the reader simply ask himself how, on such a surface, he would set about building a substantial wall, that should be able to bear weight and to stand for ages. He would assuredly look about for the largest stones he had at his disposal, and, rudely levelling the ground, he would lay these well together over a considerably larger width than he required the wall to be (suppose as at a, Fig. 2), in order to equalise the pressure of the wall over a large surface, and form its foot. On the top of these he would perhaps lay a second tier of large stones, b, or even a third, c, making the breadth somewhat less each time, so as to prepare for the pressure of the wall on the centre, and, naturally or necessarily, using somewhat smaller stones above than below (since we supposed him to look about for the largest first), and cutting them more neatly. His third tier, if not his second, will probably appear a sufficiently secure foundation for finer work; for if the earth

¹ [Where the Cathedral is surrounded by a wide marble platform with steps.]

[Version 0.04: March 2008]